Effects of the seasonal variation in the phytochemical composition and bioactivities of the wild halophyte Suaeda fruticosa

Suaeda fruticosa is an edible medicinal species belonging to the Amaranthaceae (Chenopodiaceae) family widely distributed in the Mediterranean regions, especially in Tunisia. This species shoots change their colour from green to red-violet along the different seasons, being an interesting matrix to study for its chemical composition. Therefore, in a ground-breaking study, the hydromethanolic extracts of green and red-violet Tunisian S. fruticosa shoots were profiled for their individual phenolic compounds and betalains by High Performance Liquid Chromatography coupled with a Diode-Array Detector and Mass Spectrometry by Electrospray Ionization (HPLC-DAD/ESI-MS), and the in vitro antioxidant, antibacterial, and hepatotoxic properties were also assessed. The obtained results revealed that the hydromethanolic extracts contain interesting levels of phenolic compounds especially O-glycosylated and acylated flavonoids, while betacyanins were the main betalain compounds found. As expected, red-violet shoots were richer in phenolic compounds (45.5 ± 0.2 mg/g extract) and betalains (33.3 ± 0.2 mg/g extract) than greener shoots. Flavonoid/betalains rich extracts presented lower EC50 values for ABTS+, DPPH, and TBARS; as also lower MIC values against Gram-positive bacteria. This study showed that the wild halophyte growing in a hard environment, were drought and salinity are dominant, is an important source of flavonoids and betanin, important molecules that can find application in different industries, given the constant demands for natural bioactives and colouring compounds. Overall, these natural compounds may be valorised and further investigated to validate their potential as functional ingredients.